<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>
</head>
<body>
  
</body>
<script>
  //监视的是地址的引用值
  const URL='https://www.adun.com';
  // Assignment to constant variable.
  // 常量在同一个作用域中是不可进行修改的
  // URL="哈哈哈";
  function show(){
    const URL='哈哈哈哈';
    console.log(URL);
    
    
  }
  show();

  //定义引用类型
  const Config={};
  Config.URL='https://www.adun.com';
  console.log(Config);
  
</script>
</html>